Automatic draft controller



June 18, 1935. G. J. IRSCH ET AL AUTOMATIC DRAFT CONTROLLER Filed April25, 1932 Inuani' a J I/ch faphenson Ge/o@ William B. 6

.|.r. Ill 1 1 O D Patented June 18, 1935 PATENT OFFICE AUTOMATIC DRAFTCONTROLLER George J. Irsch, Harvey, and William B. Stephenson, Chicago,Ill.

Application April 25, 1932, Serial No. 607,404

17 Claims.

The present invention relates generally to improvements in automaticdraft controllers for furnaces, and has particular reference toselfclosing suction-operable controllers for regulating the admission ofatmospheric air into the flue gas outlet passage of the heatingapparatus so as to maintain in normal operation a draft of apredetermined desired intensity in the fire box, and hence to preventthe draft from exceeding such intensity, regardless of fluctuations inthe conditions tending to induce the draft.

An important object of the present invention resides in the provision ofa novel suction-operable draft controller which is highly sensitive andaccurate in operation.

A further object is to provide a new and improved counterweight for thepivotal damper plate of the controller whichis accurately adjustableover a wide and finely graduated range to obtain the desired degree ofbalance, and particularly to adapt the controller to a large variety ofchimneys and heating installations.

Another object resides in the provision of a counterweight comprising aflowing weight which is self-adjustable in accordance with the openingof the damper plate of the controller to improve the action andtopartially counteract the tendency toward laziness as the plate isopened.

Furtherobjects and advantages will become 0 apparent as the descriptionproceeds.

In the accompanying drawing, Figure l is a fragmentary front elevationalview of a draft controller embodying the features of our invention. I

Fig. 2 is a vertical sectional View of the draft controller taken alongline 22 of Fig. 1, the damper plate being shown in closed position.

Fig. 3 is a view similar to Fig. 2, but showing the damper plate in anopen position.

Fig. 4 is an enlarged sectional detail View taken along line 44 of Fig.1.

Fig. 5 is a horizontal sectionalview on an enlarged scale of thecounterweight taken along line 5-5 of Fig. 1.

While the invention is susceptible of various modifications andalternative constructions, we have shown in the drawing and will hereindescribe in detail the preferred embodiment, but it is to be understoodthat we do not thereby intend to limit the invention to the specificform disclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the inventionv asexpressed in the appended claims.

Referring more particularly to the drawing,

the draft controller may be mounted to admit atmospheric air at anydesired point to the outlet passage for the products of combustionbetween the chimney and the heating apparatus. In its preferred form,the draft controller comprises a hood or casing it which is mounted. incommunication with the chimney draft passage (not shown) and which hasan outer vertical wall ll formed with an air inlet opening l2. A door ordamper plate I3 is mounted in operative relation to the opening l2. Inthe present instance, both the opening I2 and plate I3 are rectangularin form.

The damper plate I3 is pivotally mounted at its lower edge, and whenvclosed is disposed against the inside of the marginal edge of'theopening l2. A strip of flexible material, such as felt, is securedagainst the inside of the marginal edge of the opening I2 to cushion theplate It when moved'into closed position.

To provide a pivotal mounting therefor, the plate l3 has secured to itsback a plurality. of parallel vertical reinforcing battens or straps l5which at their lower ends are curled about a horizontal shaft l6 andsecured thereto as by means of pins ll. Opposite ends of the shaft l6are jo-urnaled in antifriction bearings I8, preferably ball bearings, ofwhich theouter raceways are mounted in brackets I9 welded to the insideof the wall I I slightly below the opening I 2.

A counterweight 20 is mounted on and normally acts in a direction toclose the damper plate 13. Thus, the counterweight '20 opposes theaction of the draft, and when properly selected and adjusted willestablish the damper plate l3 in a balanced position in which the plateis sensitively responsive to fluctuations in the draft and operable tocompensate for same by varying the effective inlet area of the openingI2. It will be evident that for a definite force counterbalancing thechimney draft, a predetermined draft will be maintained in the fire box.

The counterweight 20 is adjustable so that the draft intensity to bemaintained may be varied as necessitated by the particularcharacteristics and requirements for maximum efiiciency of the heatingsystem. In its preferred form, the counterweight 20 comprises anelongated support 2| depending from the damper plate l3 below the pivotshaft l6, and a weight 22 adjustably mount- 5 ed on the support 2!. Thesupport 2|. is in the form of an arm secured at its upper end centrallyto the lower end of the plate 13, and consists of two parallel bars 23connected at their upper and lower ends respectively by cross members 24and '25 to form an integral structure.

' counterweight 20.

The arm 2| in one position is disposed substantially in the same planeas the plate I3, but at its upper end is curved away from the front ofthe plate so as to provide clearance for the lower edge of the openingI2 in opening the plate.

The arm 2I is pivo-tally adjustable on the damper plate I3 so as toadjust the relative angular relation of the counterweight 20 as a whole.To this end, the cross member 24 constitutes a leaf hinged at its upperedge to the plate I3. A set screw 21 is adjustably threaded through theleaf 24 for engagement with the plate I3 to effect the desired angularadjustment of the arm 2|. 7 To provide means for adjusting the weight 2longitudinally of the arm 2I, the bars 23 are formed along their lengthwith regularly spaced holes 28. The weight 22 comprises a supportingbase 29 which extends transversely of the arm 2| through the spacebetween the bars 23. Braces 3|, on the base 29 are adapted to be securedto the bars 23 by means'of bolts 32 extended selectively through certainof the holes 28 at the desired point of adjustment.

To render the weight 22 adjustable transversely of the arm 2 I, itcomprises two constituent weights 33 secured to the base 29 foradjustment respectively along two parallel longitudinal slots 34. In thepresent instance, each weight 33 comprises an elongated curved tube 35having a stud 36 intermediate its ends extending through the associatedslot 34 and adapted to be secured in any desired position of adjustment.

The counterweight 20 renders the damper plate I3 self-closing. Thesuction of the draft tends to open the plate I3 against the action ofthe It will be evident that the counterweight 2|] is accuratelyadjustable over a wide and finely graduated range. Thus, thecounterweight 20 is adjustable as a whole angularly tothe damper plateI3 by turning the set screw 27. Obviously, if the arm 2| is adjustedinto the plane of the plate I3, the counterweight 20 will tend tobalance the plate I3 in closed position, while if the arm is adjustedoutwardly at an angle to the plate, the counterweight will weigh downthe plate to resist a substantial draft before the plate will open inresponse to the draft suction. The weight 22 is adjustable as a wholealong the arm 2| to vary its net effect in the different angularpositions of the damper plate A fine adjustment adapted to satisfywidely different requirements is available by adjusting the constituentweights 33 jointly or relatively to each other along the base 29. If thetwo weights 33 are positioned respectively at opposite ends of the base29, the damper plate I3 will be very sensitive to the draft in and nearits closed position, and hence will open easily and close gently withoutslamming. If the weights 33 are located side by side on the inner end ofthe base 29, the plate I3 will not close completely, and the closingaction of the weight 22 on the plate is greatly reduced. Conversely, ifthe two weights 33 are located side by side on the outer end of the base29, the closing action of the weight 22 will be at its maximum, and willhold the plate I3 in closed position against a suction of substantialforce. Itwill be evident that the weights 33 may be adjusted into anyone of a large number of relative positions. The wide and fineadjustment of the counterweight 20 is important because of the manyprevailing sizes of chimneys and the widely varying characteristics ofdifferent heating installations, as well as the different specificrequirements of a particular installation.

In the initial opening of the damper plate I3, upon an increase in theintensity of the chimney draft to the predetermined value that it isdesired to maintain and that is determined by the counterforce, i. e.the physical weight and adjustment of the counterweight 20, the airenters under a considerable velocity, and hence the plate is verysensitive to pressure fluctuations in the draft. However, as the plateI3 is caused to swing progressively toward its maximum open position, itbecomes less sensitive to changes in the draft, i. e. becomes lazy.While the effect of the counterweight 20 as a whole increases as thedamper plate I3 opens, the weights 33 are automatically self-adjustableto reduce the rate of increase so as to render the plate I3 moresensitive and accurate when open a substantial distance, therebyovercoming any lazy tendencies. Thus, the weights 33 comprise heavy ironor steel balls 31 in the sealedtubes 35, and preferably also a body ofmercury 38 for supplementing the balls and floating same. As a result,the weights 33 are sensitive floating or live weights as distinguishedfrom less sensitive dead or inert weights. The changing eifect of thecounterweight 29 is clearly illustrated in Figs. 2 and 3.

The tubes 35 are curved to control the action of the balls 31 and themercury 38. It will be evident that as the radius of each tube isincreased, the tube will tend to become straighter, so, that the flowingweight therein willend to move more rapidly and be more likely to bangagainst the ends of the tube. Conversely, as the radius of each tube isdecreased, the weight will tend to move more slowly and to stay more inone place, thus becoming less sensitive. We have found that satisfactoryresults can be obtained wlth a tube radius of from eight to fourteeninches, and

prefer to use a radius of approximately twelve inches.

We claim as our invention:

1. An automatic draft controller comprising, in combination, a hoodhaving a vertical well formed with an air inlet opening, a damper platefor closing said opening, antifriction rollerbearings supporting saidplate. at its lower end for pivotal movement about a horizontal axisinto and out of closed position, 9, depending arm pivotally mounted atits upper end on said plate, said arm extending substantially below saidplate, means for adjusting the angular position of said arm relative tosaid plate, and a weight on the free end of said arm.

2. An automatic draft controller comprising, in combination, a hoodhaving a vertical wall formed with an air inlet opening, a damper platefor closing said opening, 2. depending arm pivotally mounted at itsupper end on said plate,

means for adjusting the angular position of said arm relative to saidplate, a member'adjustable longitudinally of said arm and extendingtransversely thereof, and two weights independently adjustable on saidmember, each of said weights comprising a closed container and aconfined shiftable weight in said container.

3. An automatic draft controller comprising, in combination, a hoodhaving a vertical wall formed with an air inlet opening, a damper platefor closing said opening, antifriction bearings supporting said platefor pivotal movement about itslower end into and out of closed position,a. depending arm pivotally mounted'at'its upperend on said plate, meansfor adjusting the angular position of said arm relative to said plate,amember adjustable longitudinallyof said arm and extendingtransverselythereof, and two weights independently adjustable on-saidmember.

4. An'automatic draft controller comprising, in combination, a hoodhaving a vertical wall formed with an air inletopening,'a pivotal damperplate for closing said opening, a depending arm pivotally mounted at itsupper end on said plate, means for'adjusting'the angular position ofsaid arm relative tosaid plate,a member adjustable. longitudinally ofsaid arm, and two weights independently adjustable on said member. 1

' 5. An automatic draft controller comprising, in combination, meansdefining an air'inlet opening, a damper plate pivotally mounted inoperative relation tosaid opening, a'counterbalancing arm hinged to saidplate and extending acrossthe pivotal axis of said plate, means foradjusting the angular position of said arm relative to said plate, and aweight adjustably mounted on said arm.

6. An automatic draft controller comprising, in combination, meansdefining'an air inlet opening, a generally vertical damper platepivotally mounted at its lower end on a horizontal axis in operativerelation to said opening, a counterbalancing arm mounted on said plateand depending therefrom below said axis, a support on said arm, twoconstituent weights mounted on said support for independent adjustmenttransversely of said axis, said weights being adjustable into differentrelative positions, each weight comprising a closed curved tube, an ironball freely movable in said tube, and a body of mercury for floatingsaid ball in said tube.

7. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a generally vertical damper platepivotally mounted at its lower end on a horizontal axis in operativerelation to said opening, a counterbalancing arm mounted on said plateand depending therefrom below said axis, a support on said arm, twoconstituent weights mounted on said support for independent adjustmenttransversely of said axis, said weights being adjustable into differentrelative positions, each weight comprising a container and a heavy metalball freely movable in said container.

8. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a pivotal damper mounted on a horizontalaxis in operative relation to said opening, and a counterweight for saiddamper, said counterweight comprising a support having two parallelguides extending transversely of said axis and when said door is closedextending horizontally across said axis, and two similar independentweights slidably mounted side by side on said support for adjustmentrespectively along said guides transversely of said axis and intoposition at one or the other side or respectively at opposite sides ofsaid axis.

9. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a damper plate pivotally mounted to closesaid opening, and a counterweight mounted on said damper plate formovement therewith and tending to pivot said plate in a direction toclose said opening, .said counterweight comprising a closed generallytubular container extending generally transversely of the pivotal axisof said plate, a large iron ball freely movable in said container,

said ball being slightly less in diameter than said container, and abody of mercury in said container for floating said halt-said ball andmercury being movableunder the influence ofgravity imparted in responseto the pivotal .movement of said plate to modify the action of saidcounterweighton said plate.

10. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a damper plate mounted to close saidopening, and a pivotally adjustable counterweight mounted on said damperplate for movement therewith and tending to move said plate inadirection to close said opening, said counterweight comprising acontainer and a flowing weight insaid container, said weight beingfreely movable under the influence of gravity imparted in response tothe movement of said plate to modify the action of said counterweight onsaid plate.

11. An automatic draft controller comprising,

in combination, means defining an air inlet opening, a generallyvertical damper plate pivotally mounted on a horizontal axis inoperative relation to said opening, a counterbalancing member hinged tosaid plate and dependingbelow the pivotal axisthereoi, means foradjusting the ,angular position of said member relative to said plate,and a weight including a level-seeking mass on said member, said mass inseeking different horizontal levels under the influence of gravity uponmovement of said plate into different angular positions beingself-shiftable transversely of said axis and relatively to said memberto modify the action of said weight on said plate.

12. An automatic draft controller comprising, in combination, a wallformed with an inlet opening, a pivotal damper plate for closing saidopening, and a counterbalancing means for said plate, said meanscomprising an elongated arm pivotally secured at one end to said plate,the free end of said arm extending across the axis of rotation of saidplate and substantially beyond one end of said plate, said arm being.angularly adjustable from a position in the plane of said plate intodifferent angular relations to said plate, and a weight adjustablymounted on said arm.

13. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a damper plate pivotally mounted on ahorizontal axis in operative relation to said opening, an elongateddepending counterbalancing arm secured at its upper end to said plate,and extending below said axis, said arm being formed with a longitudinalslot, a support mounted on said arm and extending transversely thereofthrough said slot,means for adjustably securing said support indifferent positions along said arm, said support being formed with twoparallel longitudinal slots, and two independent weights mounted on saidsupport for adjustment respectively along said last mentioned slots,said weights being adapted to be located side by side or in anystaggered relation within the limits of said last mentioned slots, saidarm, support and weights constituting a counterweight tending to pivotsaid plate in a direction to close said opening.

H. An automatic draft controller comprising, in combination, a hoodhaving a generally vertical wall formed with an air inlet opening, adamper plate pivotally mounted in operative relation to said opening, adepending counterbalanclng arm connected at one end to said plate formovement therewith, the other end of said arm extending below thepivotal axis of said plate and being angularly adjustable relative tothe plane of said plate, a cross member on the lower end of said arm,and weight means mounted on said cross member for adjustmenttransversely of said axis selectively into position at either side or atboth sides of said arm.

15. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a generally vertical damper platepivotally mounted at its lower end on a horizontal axis in operativerelation to said opening, a counterbalancing arm mounted on said plateand depending 'therefrombelow said axis, a guide member mounted on thefree end of said arm and extending generally transversely of said axis,and a weight supported by said guide member to move freely along saidguide member generally transversely of said axis under the influence ofgravity imparted in response to the pivotal movement of said plate,whereby the counterbalancing effect of said weight is modified fordifferent angular positions of said plate.

16. An automatic draft controller comprising, in combination, meansdefining an air inlet opening, a, generally vertical damper platepivotally mounted at its lower end on a horizontal axis in operativerelation to said opening, a counterbalancing arm mounted on said plateand depending therefrom below said axis, an elongated curved generallyhorizontal guide member mounted on the free end of said arm andextending generally transversely of said axis, said member beinglongitudinally concave upwardly, and a solid weight supported'by saidguide member for free rolling movement along said member generallytransversely of said axis under the influence of gravity imparted inresponse to the pivotal movement of said plate, whereby thecounterbalancing effect of said weight is modified for different angularpositions of said plate.

17. An automatic draft controller comprising, in combination, meansdefining an air'inlet opening, a generally vertical damper platepivotally mounted at its lower end on a horizontal axis in operativerelation to said opening, a counterbalancing arm mounted on said plateand depending therefrom below said axis, a generally horizontalelongated container mounted on said arm below said axis and extendinggenerally transversely of said axis, and a body of mercury freelymounted in said container and adapted to seek diiferent levels uponmovement of said plate into different angular positions, whereby thecounterbalancing efiect of said body of mercury is modified.

GEORGE J. IRSCH. WILLIAM B. STEPHENSON.

